Abstract:

There is described a manufacturing method of motor vehicles which achieves
the object of reducing the costs deriving from the manufacturing of
vehicles belonging to different segments and the costs deriving from the
traditional assembly of vehicles which starts from the external shell
onto which the elements forming the interiors and the mechanical members
are assembled, by suggesting the arrangement of a single self-supporting
structural element formed by composite material, already provided with
many interior elements, to which a new other interior elements, bodywork
elements and mechanical elements can be connected in any assembly order.

Claims:

1. A manufacturing method of motor vehicles mainly formed by bodywork
elements, interior elements and mechanical members, which comprises the
following steps:a lower self-supporting structural element is arranged,
defining at least the bottom of the passenger compartment of a vehicle,
onto which mechanical members, elements forming the bodywork and elements
constituting the interiors are to be connected;one or more of said
interchangeable bodywork elements defining the segment to which the
vehicle belongs are independently arranged;one or more of said mechanical
elements defining the vehicle performance in relation to the segment to
which it belongs are independently arranged;one or more of said elements
forming the vehicle interiors in relation to the segment and price range
to which it belongs are independently arranged;one or more bodywork
elements, mechanical elements and interior elements are assembled onto
said lower self-supporting structural element in any sequence order.

2. A method according to claim 1, wherein said lower self-supporting
structural element is originally provided with a set of interior
components, said interior components possibly being pre-moulded in a
single structural block and being already pigmented in the required
colour.

3. A method according to claim 1, further comprising a step of arranging
false frames adapted to allow to assemble various types of preassembled
mechanical means for one step of assembling a vehicle.

4. A method according to claim 3, wherein the mutual pre-assembly of some
mechanical members is concurrently arranged during said step of
assembling separately from the remaining whole.

5. A method according to claim 3, wherein the mutual pre-assembly of some
bodywork members is concurrently arranged during said step of assembling
separately from the remaining whole.

6. A method according to claim 3, wherein said assembly is performed after
a further step of arranging assembly members, such as holes, screws
and/or joints.

7. A method according to claim 3, wherein said assembly is performed
following a further step of arranging joints and/or glues.

8. A method according to claim 1, further comprising a step in which there
are arranged templates adapted to facilitate the pre-assembly of
mechanical and/or bodywork and/or interior assemblies.

9. A method according to claim 1, wherein tyres of different diameter are
arranged in order to vary the wheelbase of the assembled vehicle.

10. A method according to claim 1, comprising a further step of stiffening
said lower self-bearing structural element, which comprises a step of
injecting, into the internal cavities, a foam of variable density in
relation to the mechanical features which are intended to be obtained by
said element and/or in relation to the mechanical-vibrational features of
the mechanical members coupled either directly thereto or not.

11. A method according to any preceding claim, wherein said lower
self-supporting structural element and/or said one or more
interchangeable bodywork elements is/are made of composite plastic
material, preferably an ABS and polycarbonate compound, possibly filled
with fibreglass.

12. A method according to claim 11, wherein said lower self-supporting
structural element and/or said one or more interchangeable bodywork
elements are cables, and foam is preferably injected in said cavities.

13. A method according to any of the preceding claims, wherein said foam
is polyurethane.

14. A method according to any preceding claim, wherein said lower
self-supporting structural element is basin-shaped.

15. A method according to any preceding claim, wherein said openings are
made in said lower self-supporting structural element at a given height
with respect to the lowest level, for the insertion from the outside of
parts belonging to other assembly elements.

16. A vehicle obtained by a manufacturing method according to any of the
preceding claims.

17. A vehicle according to claim 16, wherein the floating level in water
is such that any possible opening in the vehicle remains over said
floating level.

18. A vehicle according to claim 16, wherein check valves are made at the
bottom of said lower self-supporting structural element, which valves
open outwards allowing water to exit from the vehicle, and close in the
case of water entering from the outside.

Description:

FIELD OF THE INVENTION

[0001]The present invention relates to a manufacturing method of a motor
vehicle and a motor vehicle thereby obtained, specifically with bodywork
formed by composite materials.

STATE OF THE ART

[0002]Marketing strategies have forced automotive manufacturers to access
the highest possible number of segments. Major manufacturers of large
luxury cars have started producing city and medium-sized cars, while
attempting to maintain high manufacturing and quality standards.

[0003]The different manufacturing sectors require very different technical
solutions, e.g. the self-supporting structure of a city car is very
different from that of a small off-road vehicle, and is different from
that of a flagship vehicle, etc.

[0004]Many companies tend to stipulate agreements with competitors for the
development of motor vehicles so as to share the engineering and
manufacturing costs of common parts of cars in the same segment.

[0005]Similarly, some manufacturers develop engines of a certain type
which will equip motor vehicles of competitors with which they have
established commercial agreements.

[0006]It is also known that in the scope of a same group, a same floor bed
is shared by cars of the same segment or by cars of slightly different
segments, for example a saloon and its estate car version.

[0007]In actual fact, the concept is that of recycling a same structural
element cooperating with further structural elements, such as the roof,
the cowling, etc., so as to form a single, sufficiently rigid body.

[0008]Therefore, the characteristic steps of the manufacturing of cars
consist in assembling a characteristic load-bearing structure of a
vehicle belonging to a given segment starting from a floor bed, by means
of weldings and connection elements. Further elements are then added,
such as for example the engine and the transmission which are connected
together and with said structure. Further elements are later added to the
whole.

[0009]The interiors are left for last, also to allow the passage of wires
from the front to the back.

[0010]It is thus apparent that a first drawback of the current way of
designing and manufacturing cars derives form the fact of reusing only a
small portion of the self-supporting structure of a motor vehicle for
manufacturing further vehicles of the same segment. Another drawback
depends on the fact that the assembly of the car interiors forces workers
and robotized arms to enter inside the structure, e.g. from a side
access, to assembly moulding, panelling, upholstery, etc.

SUMMARY OF THE INVENTION

[0011]It is the object of the present invention to provide a manufacturing
method of motor vehicles which allows to cut both engineering and
manufacturing costs of common elements, and the assembly cost of the
vehicles.

[0012]A further object of the invention is to provide motor vehicles
belonging to different segments sharing a structural element which is
self-supporting in itself.

[0013]The present invention thus aims to reach the above-described objects
by making a method for manufacturing motor vehicles mainly formed by
bodywork elements, interior elements and mechanical members, which
comprises the following steps: [0014]a lower self-supporting structural
element is arranged, defining at least the bottom of the passenger
compartment of a vehicle, onto which mechanical members, elements forming
the bodywork and elements constituting the interiors are to be connected;
[0015]one or more of said interchangeable bodywork elements defining the
segment to which the vehicle belongs are independently arranged;
[0016]one or more of said mechanical elements defining the vehicle
performance in relation to the segment to which it belongs are
independently arranged; [0017]one or more of said elements forming the
vehicle interiors in relation to the segment and price range to which it
belongs are independently arranged; [0018]one or more bodywork elements,
mechanical elements and interior elements are assembled onto said lower
self-supporting structural element in any sequence order.

[0019]According to an aspect of the invention, the lower self-supporting
structural element is originally provided with a set of interior
components, said interior components possibly being pre-moulded in a
single structural block and being already pigmented in the required
colour.

[0020]According to a further aspect of the invention, said device is
easily applied when one intends to manufacture vehicles belonging to many
different commercial segments while limiting investments, because the
manufacturing differentiation would be exclusively limited to said
bodywork element sets, such as the possible roof, the windscreen, the
possible doors, the cowling, etc., and to some mechanical members, such
as the suspensions, the transmission, the engine, the driveline and the
wheels.

[0021]Advantageously, it is possible to make cars belonging to different
segments, e.g. off-road cars, sports cars, city cars, vans, etc.,
starting from a single lower structural element.

[0022]Specifically, said element is self-supporting, meaning that the main
mechanical members are either directly or indirectly connected to it
without involving further structural elements.

[0023]Furthermore, it is possible to assemble the elements forming the
interiors before having mounted a bodywork element set, e.g. the
dashboard can be assembled before mounting the windscreen pillars and the
roof so as to prevent workers or mechanical arms from having limited,
inconvenient access to the vehicle.

[0024]Said elements forming the interiors can be integrated from the
beginning in said lower self-supporting structural element, thus
drastically reducing the number of manufacturing steps.

[0026]Further features and advantages of the invention will be more
apparent in the light of the detailed description of a preferred, but not
exclusive embodiment of a vehicle resulting from the application of the
manufacturing method object of the present invention, illustrated by way
of non-limitative example, with the aid of the accompanying drawings, in
which:

[0027]FIG. 1 shows a lower element 1, which is characterized in that it is
self-supporting and adapted to be assembled with different sets of
elements defining the bodywork of the vehicle and consequently the
segment to which it belongs;

[0028]FIG. 2 shows a preferred embodiment of said element which is
obtained by the assembly of portions in itself;

[0030]FIG. 4 shows some preferred embodiments of vehicles obtained from
said same lower element 1 onto which different sets of mechanical,
bodywork and interior elements are applied.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

[0031]The method according to the present invention comprises a step of
engineering of a lower self-supporting structural element, already
provided with many internal components, onto which the mechanical
elements, such as the transmission, the driveline and the engine, other
interior elements and bodywork elements are subsequently assembled in any
order.

[0032]Specifically, the lower self-supporting structural element may be
already provided in origin with a set of interior components, such as for
example dashboard, object holder panels, soundproofing panels, etc.,
which may even be pre-moulded in a single structural block, and which are
already pigmented in the required colour, thus avoiding subsequent
manufacturing steps, such as those of assembly, painting or rust
treatment, etc., features of the traditional procedures based on
structural metal.

[0033]Other elements, such as for example the seats, the upholstery, can
be inserted later.

[0034]Said bodywork elements can even considerably vary the shapes, size
and functions of the vehicle that they form.

[0035]By implementing said method, there may be obtained, for example, a
lower element like that shown in FIG. 1.

[0036]This may be in turn formed by portions made separately and then
assembled for manufacturing needs, as shown in FIG. 2, wherein a central
element 1.1 is completed on each side by a side guard of which only the
right-hand one 1.2 is shown. The various parts may also be joined
together with techniques known in themselves, e.g. by gluing, screwing or
ultrasound welding.

[0037]The material used for said preferred embodiment, specifically for
the lower self-supporting structural element, and for the interior
components of which it is already provided, is a hollow composite plastic
material in which a foam may be injected.

[0038]The composite plastic material may be a compound formed by ABS and
polycarbonate, possibly filled with fibreglass, injected into the
compound for reinforcing some parts most subject to stress.

[0039]The foam may be polyurethane and may assume a double function: to
soundproof the vehicle and confer further rigidity thereto.

[0040]Advantageously, in relation to the vehicle type, to the total
weight, according of the set of mechanical members used, and for the
destination of use of the vehicle, the density of said foam can be varied
thus obtaining more or less rigidity and/or soundproofing of the single
supporting element i.e. of said lower element 1.

[0041]Furthermore, electric wires and/or other components, such as for
example cable-holder sheathing, the terminals of which protrude to be
then connected to other parts of the vehicle, may be further inserted in
said foam.

[0042]FIGS. 1 and 2 highlight the shape of said basin-shaped lower
element, in which in addition to the various pillars and reinforcement
side-members there are visible two openings 1.3, symmetric with respect
to the middle line of the element, adapted to accommodate the control
pedal board of the vehicle, which is inserted from the outside through
said openings, so as to be able to indifferently contemplate either
right-hand drive or left-hand drive.

[0043]FIG. 3 shows some elements forming the bodywork which can be mounted
on said lower element 1 in relation to the reference segment of the
vehicle to be made.

[0045]Said covering may be assembled separately from the rest of the
vehicle and may superimposed onto it after having connected the elements
forming the interiors to the vehicle.

[0046]When a vehicle, e.g. a van, is intended to be constructed, a body 5,
either glazed or not, is preferred to said tail end 4.5, e.g. like that
shown in the figure, which perfectly joins with said upper covering 4.

[0047]When instead a so-called pick-up vehicle is required, an element 6
is mounted instead of said element 5 which, along with said lower element
1 forms an open bodywork for loading cargo, etc.

[0048]In such a case, a further alternative is that of completing the rear
part of the vehicle with a boot 7, like the one shown in the figure.

[0049]If the vehicle is not further lengthened for the use of elements
such as 5 and 6, the vehicle is completed with a bumper 8 of short type,
otherwise a bumper which, despite being interchangeable with respect to
the shorter type, is longitudinally longer to better couple with said
elements 5 or 6.

[0050]FIG. 4 shows, by way of example, some vehicle versions belonging to
different segments, in which the lower element 1 is always recognizable.

[0051]The possible need to vary the wheelbase of the vehicle may be solved
by using wheels of different diameter.

[0052]With regards to mechanics, in order to make the combination of
various different technological solutions possible, the mechanical parts
are connected to said lower element 1 by means of false frames
independently preassembied and subsequently connected to the lower
element 1 during the final assembly step. For example, FIG. 4 shows a
front false frame 10, and a rear false frame 11. For example, a wheel
axle, with corresponding suspensions, an engine-transmission assembly or
other may be preassembled into the false frame.

[0053]These thus act as interface with said lower element 1, meaning, that
the connection means, e.g. joints and holes between said false frames and
the lower element 1 remain constant regardless of the shape, number and
arrangement of the connection means between said false frames and the
corresponding mechanical members.

[0054]Specifically, it is particularly advantageous to prepare
appropriately templates for allowing the asynchronous assembly of the
mechanical parts, the pre-assembled whole of which is connected to said
lower element 1 by means of said false frames.

[0055]Finally, it is possible by means of the method described above to
very rapidly produce a vehicle with features and appearance adapted to
the various markets, also because it may not be necessary to paint the
bodywork, if it is already formed by pigmented composite material, thus
minimising the investments that manufactures are forced to make to
rapidly satisfy customer requests.

[0056]According to another aspect of the invention, said elements forming
the bodywork may also be made of composite material, e.g. already
pigmented, and connected to said lower element 1 by means of glues or by
means of joints and/or connection members, such as screws, bolts, etc.

[0057]In such a manner, there is obtained a vehicle in which the shell and
the supporting structure are entirely made of composite material, with a
further cutting of costs related to the easy implementation of the
various steps of the manufacturing process, grouped together in a single
step.

[0058]The plastic material of which the various parts described above are
made, allows to obtain a particularly light vehicle. For example, a
vehicle with a total weight of approximately 600 kg may be obtained.

[0059]Furthermore, the basin shape of the self-supporting structural
element, combined with the light-weight of the material, contributes to
obtain another important feature: the floating of the vehicle in case of
immersion in water, even accidental. This is due to the fact that the
floating level in water of the vehicle may be kept high, e.g.
approximately 20 cm over the lowest point of the self-supporting
structural element. In this manner, any possible opening of the vehicle,
such as for example the openings 1,3 for inserting the pedal board, may
remain over the floating level. Similarly, the lower edge of the doors
will be at a higher level than the floating level.

[0060]Preferably, at the bottom of the basin of the self-supporting
structural element, appropriate check valves are made which open outwards
allowing water to exit from the vehicle, e.g. after an inside washing,
and close in case of attempt of water seeping from the outside. Said
valves may be made of known type plastic. It is not necessary to provide
further details of the manufacturing method because a person skilled in
the art may apply known procedures and machinery for implementing the
various steps of the method once it is known on the basis of that
disclosed herein.

[0061]The particular embodiments here described do not limit the content
of this application which covers all the variants of the invention as
defined in the claims.